--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/oops/arrayOop.hpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,70 @@
+/*
+ * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// arrayOopDesc is the abstract baseclass for all arrays.
+
+class arrayOopDesc : public oopDesc {
+  friend class VMStructs;
+ private:
+  int _length; // number of elements in the array
+
+ public:
+  // Interpreter/Compiler offsets
+  static int length_offset_in_bytes()             { return offset_of(arrayOopDesc, _length); }
+  static int base_offset_in_bytes(BasicType type) { return header_size(type) * HeapWordSize; }
+
+  // Returns the address of the first element.
+  void* base(BasicType type) const              { return (void*) (((intptr_t) this) + base_offset_in_bytes(type)); }
+
+  // Tells whether index is within bounds.
+  bool is_within_bounds(int index) const        { return 0 <= index && index < length(); }
+
+  // Accessores for instance variable
+  int length() const                            { return _length;   }
+  void set_length(int length)                   { _length = length; }
+
+  // Header size computation.
+  // Should only be called with constants as argument (will not constant fold otherwise)
+  static int header_size(BasicType type) {
+    return Universe::element_type_should_be_aligned(type)
+      ? align_object_size(sizeof(arrayOopDesc)/HeapWordSize)
+      : sizeof(arrayOopDesc)/HeapWordSize;
+  }
+
+  // This method returns the  maximum length that can passed into
+  // typeArrayOop::object_size(scale, length, header_size) without causing an
+  // overflow. We substract an extra 2*wordSize to guard against double word
+  // alignments.  It gets the scale from the type2aelembytes array.
+  static int32_t max_array_length(BasicType type) {
+    assert(type >= 0 && type < T_CONFLICT, "wrong type");
+    assert(type2aelembytes[type] != 0, "wrong type");
+    // We use max_jint, since object_size is internally represented by an 'int'
+    // This gives us an upper bound of max_jint words for the size of the oop.
+    int32_t max_words = (max_jint - header_size(type) - 2);
+    int elembytes = (type == T_OBJECT) ? T_OBJECT_aelem_bytes : type2aelembytes[type];
+    jlong len = ((jlong)max_words * HeapWordSize) / elembytes;
+    return (len > max_jint) ? max_jint : (int32_t)len;
+  }
+
+};